1. Field of the Invention
The invention generally relates to telephonic and radio communications, and more particularly, to wireless communications using simplex and duplex protocols.
2. Background Description
There are three ways for data communications to flow between electrical or digital devices: simplex, half-duplex and full duplex. In simplex communications, information only flows in one direction, as from a radio station transmitter to a home radio receiver. In true simplex communications, there is thus no return signal. In half-duplex communications, information flows in both directions, but only in one direction at a time. Examples of such half-duplex communications include CB, walkie-talkie, or marine radio communications where one party must complete their transmission before the other party can reply. In full-duplex communications, data is transmitted in both directions simultaneously. A common example is a telephone conversation in which both parties are talking and listening simultaneously. Full-duplex is sometimes used in modern computer and video networks to facilitate real-time exchange of information.
Today, personal communicators (cellphones, two-way radios, handheld computers, etc.) abound, and short voice messages are often transmitted over half-duplex channels because pressing a push-to-talk (PTT) button to instantly connect to another person's communicator is faster than dialing the person's conventional duplex telephone number. However, current personal communications devices are not capable of seamlessly switching from simplex or half-duplex mode to full-duplex mode. Thus, various problems arise when a recipient of a simplex message (e.g., either a true simplex communication or one-part of a two-way half-duplex communication) wishes to transition to full-duplex mode.
For example, if a conventional duplex communication protocol is known, the transition occurs after the protocol is speed-dialed or dialed by hand. Although effective, this method is time consuming. It also requires focus and attention, which may not be available if the user is preoccupied, such as, for example, driving a vehicle or otherwise engaged in another activity. The problem only worsens when the other party's telephone number is not known, in which case the call is either delayed or not placed at all. Thus, a need exists for automatically and seamlessly converting a simplex (or half-duplex) communication into a duplex communication.